I accidentally deleted all my contacts and appointments on my mobile device. I thought, when I start synchronizing, the system will ask me if there is a mass update.
Instead all contacts and appointments in Sunbird are also deleted.
Is there any way to restore the data on my PC?

I still have most of the data on my older mobile device. So I may be able to sync this data back to Sunbird and then I have everything and sync it back onto my mobile device.
Unfortunately I can only find an option to sync the data from PC to mobile device. I can not find an option to sync the data from my mobile device to my PC.

I'm sorry you had this problem. Unfortunately, ActiveSync doesn't ask a confirmation when there are a lot of deletions during the synchronization. So if all the items are removed on the mobile device, the synchronization will remove them on the desktop. But this feature should be provided in a next version of BirdieSync to avoid this kind of problem.

Regarding the appointments, I am not sure there is a way to recover them. There is sometimes a possibility with contacts. If you need it, I can contact you by email about it.

If you want to synchronize your data from the mobile device to the PC, you must first have no ActiveSync/WMDC partnership with this mobile device. Then you must synchronize in empty address books and calendars choosing "Combine" option when you establish the partnership if you are on Windows XP (this is by default on Vista).

Were you synchronizing several address books and calendars ?
Did you use the BirdieSync options ("link calendar to contact/appointment/task categories") ?

In any case, please BACKUP the content of your other mobile device and your Thunderbird and Sunbird profiles as mentioned in this FAQ topic.

I made a Backup on my older Pocket PC, transferred this backup to my new one, restored all the data and the sync putall the contacts and appointments back to thunderbird.
Wow, that was a close shave.
There should definitly be an option to transfer data from mobile to desktop, from dessktop to mobile and both ways.

Ihave almost all of my data back, because my older pda just synchronized last friday for the last time